the weapon reach effect is explained in the manual, but I understand your point : many mechanisms are not, lest you would have a compendium of 2500 pages
weapon reach : if your is greater than your foe, then he has a moral check to do in order to attack. If he fails, he cant attack, if he passes, he takes one hit and can attack.
if you have any question, the csipgs newsgroup could have responded to you. Now that his forum is active, most of you questions you can ask will be answered too I guess.